Compact, Reliable Transformers
 

Is there a particular make and model of a small, single-plug voltage transformer that anyone would recommend? We need to take US 110/120V and step it down to Japan 100V to run some kitchen appliances.

I'd assume that just about all such transformers are made in China with the same basic design and commodity parts.

WHat wattage are you looking at?

Watts, I am not sure - I just need to step down USA household current to match Japan household current.

In this use case you will need a transformer that can handle the wattage of the appliance you're plugging into it. Overloading a transformer will just burn it out and require a new one.

Look at the appliance label where it shows things like the model number. There will be a wattage rating. What is the appliance?

For Japan you also need to consider the frequency:- 50hz or 60Hz. Depends on the area
https://en.wikipedia.org/wiki/Mains_...ity_by_country
https://en.wikipedia.org/wiki/Electr...ector_in_Japan

How long will you be in Japan?
Plugs will be different
What type of appliances?
Probably better just to buy new appliances

No, this is the opposite - I am bringing Japanese kitchen appliances back to use in the USA.

The unit is the Hitachi XV100BKM, but I am not certain of the electrical specifications

OK. Is it worth the hassle?
You need the full electrical specifications. Voltage frequency power

https://global.rakuten.com/en/store/.../item/2311753/
Wh/h means nothing to me. 1.559kW maybe :confused:

A Wh/h is a Watt-hour per hour, or a Watt. 155.9W seems like a very low power draw for a rice cooker, so I don't think I believe these numbers.

[MENTION=14516]bocastephen[/MENTION], please just look at the specs label on the rice cooker and report back its wattage rating (or volts and amps, if it doesn't show watts).

It's quite likely this rice cooker will work fine on American 120V/60Hz power. The higher voltage is probably well within its heating element's tolerance, and the electronics may well run on a power supply that doesn't care about the voltage or frequency.

It's your call whether you're willing to take the chance of plugging it in to find out.

And the electronics may well cook if it does not like the power input.
It is not unusual for a manufacturer to have small technical product variations for different markets.

Yeah, those units don't make any sense to me.

However, I had more luck with an image search--I found part of the panel, it said 1400W.

If your rice cooker won't accept US power, leave it. A transformer that can handle 1,400W is big, heavy and probably not too much cheaper than the rice cooker itself.

Heating elements generally don't have much tolerance. The problem is that the heat they produce goes up at the square of voltage. Going from Japanese 100V power to American 120V power means the heating element produces 44% more heat. I found an image of the back panel that says 1,400W. Even if the heating element can take it a standard US outlet is only rated for 15A--this would draw 16.8A.

Me neither. (I am a Mechanical Engineer) But my "convert.com" program, under energy tab, does have 1 watt-hour = 3.6 kilojoules. A kW is kJ/sec . And [Wxh]/h=W (Dimensional analysis)

No, the voltage is still 120 V. 1400 W/ 120V = 11.6 A.

A friend who is an electrical engineer got tired of waiting for his toast in the morning, so he plugged his toaster into an autotransformer and boosted the voltage to 160 volts. Toasting time dropped from a leisurely seven minutes to two and a half. As far as I know, the toaster has survived the experience so far - though it's only been running in turbo mode for a few months. He told me that the nichrome wire used in heating elements generally has a pretty high tolerance.

No. You have an element that dissipates 1,400W when fed 100V. That means it's drawing 14A and thus has a resistance of 7.1428 ohms. Now you feed 120V through 7.1428 ohms and you get 16.8A. 16.8A @ 120V = 2016W.

I meant to produce the sort of heat the unit was designed for. Sure, you can crank it up like this (it will cut the life substantially, but for what he's doing that very well might be worth it, especially as the base life is so long) but a toaster is a case where you can tolerate a pretty extreme overheat without breaking the operation of the device.

I mentioned this before in another thread -- I purchased a Zojirushi IH pressure-type rice cooker at Costco in Japan and using it in the US without a transformer. I suspect that because it is microprocessor-controlled that it monitors the temperature and makes adjustments as needed so that the higher voltage doesn't result in higher heat. It certainly doesn't feel hotter than normal. I've been meaning to measure the current draw to see if it is automatically compensating, but just haven't gotten around to it. While it works for me, you'll have to decide for yourself if you want to take the risk. I just thought I'd provide my experience as a data point.

For transformers, check out the Book-Off stores in the LA-area. I have a couple of transformers that step down from 120V to 100V and are rated for 1,400 or 1,500 watts. They were purchased as used items at the Costa Mesa Book-Off store. One is a Sanyo, the other a Nissin. I believe both were made in Japan. Cost was $40 and $45. Book-Off stores in the US buy and sell used electronics, fashion, household, and other items, similar to the other xxx-Off stores in Japan. The transformers were probably obtained from Japanese company employees who were working in the US, before transferring back to Japan.

The transformers aren't too big, maybe like a 5" cube, but they are relatively heavy. Sorry for not having exact details, but I'm currently in Thailand and can't check.

I just did an online search, and I believe that the Sanyo transformer is a model TSD-15U, with the following specs:

Input: AC 120V, 50/60Hz
Output: AC 100V
Power: 1500VA

Ahhh yes thanks. Resistance stays constant in the device so current and wattage change.

Perfect, thank you!

Just had lunch with said friend. As I suspected, I'd misremembered both toasting times and the voltage he's toasting at. It's just 140. That reduced toasting time from about four minutes to two and a quarter. I have a feeling a 17% increase in input voltage will result in a barely measurable reduction in heating element life.